This tool is used to convert MPEG-4 Audio (m4a) to Free Lossless Audio Codec (flac).

M4A is a file extension for an audio file encoded with advanced audio coding (AAC) which is a lossy compression. M4A was generally intended as the successor to MP3, which had not been originally designed for audio only but was layer III in an MPEG 1 or 2 video files.

Free Lossless Audio Codec is an audio coding format for lossless compression of digital audio. Digital audio compressed by FLAC's algorithm can typically be reduced to 50–60% of its original size and decompressed to an identical copy of the original audio data.